Hydrochloric Acid → (R)-2-((tert-Butoxycarbonyl)amino)-4,4-dimethylpentanoic acid

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Reaction Steps

N-tert-Butoxycarbonyl-3-tert-butyl-D-alanine methyl ester (example 5A, 60 g, 231 mmol) is dissolved in THF p.a. (463 ml). At RT, a solution of lithium hydroxide monohydrate (19.4 g, 462.7 mmol) in water (463 ml) is slowly added dropwise. When the HPLC chromatogram (method 1) shows complete conversion (about 20 h), the reaction mixture is cautiously adjusted to pH 3-4 using 1 N aq. hydrochloric acid while cooling in ice. Solid sodium chloride (150 g) is added to the reaction mixture, which is then extracted twice with ethyl acetate (500 ml). The combined org. phases are washed with a sat. sodium chloride solution and then dried with sodium sulfate and filtered. The filtrate is concentrated on a rotary evaporator and dried under high vacuum. 55.4 g (98% of theory) of the title compound are obtained.

Provenance & Evidence